JP6798620B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In order to improve the steering stability on a dry road surface, it is conceivable to set a wide land width of the tread portion with the aim of ensuring the tread rigidity. However, in this case, the ground contact pressure at the center of the width direction of the land portion decreases, the ground contact length of the land portion in the tire circumferential direction becomes shorter in the ground contact region, and the end portion of the ground contact length becomes dented inward to improve the ground contact property. Get worse. Therefore, the steering stability performance on a dry road surface may deteriorate. In addition, the decrease in the ground contact pressure at the center of the land portion in the width direction may reduce the drainage performance and the steering stability performance on a wet road surface.

Conventionally, for example, in Patent Documents 1 to 3, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface are improved by configuring the land contact patch so as to project in the center in the width direction. Is shown. Further, for example, in Patent Document 4, while the center main groove has a zigzag shape, the rigidity of the land portion is obtained by terminating the lug groove formed in the land portion adjacent to the center main groove in the land portion. It has been shown that the steering stability on a dry road surface and the steering stability on a wet road surface are compatible at a high level.

Japanese Unexamined Patent Publication No. 2013-189121 Japanese Unexamined Patent Publication No. 2016-002890 Japanese Unexamined Patent Publication No. 2014-118123 JP-A-2017-30556

However, in recent years, as the performance of vehicles has been improved, it has been desired to further improve the steering stability performance on dry road surfaces and the steering stability performance on wet road surfaces. In particular, when the main groove has a zigzag shape, the ground contact pressure near the groove edge becomes non-uniform, so that the ground contact length in the tire circumferential direction of the land portion adjacent to the tire width direction of the main groove becomes short, and the dry road surface It was found that it causes the steering stability performance on wet roads and the steering stability performance on wet roads, and as the performance of the vehicle improves, the steering stability performance on dry roads and the steering stability performance on wet roads will be further improved. It is desired to plan.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving steering stability performance on a dry road surface and steering stability performance on a wet road surface.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to one aspect of the present invention has a zigzag-shaped circumferential main groove extending in the tire circumferential direction on the ground contact surface of the tread portion and the circumferential main groove. Each land portion is formed on both sides of the circumferential main groove in the tire width direction with the groove as a boundary, and each contact patch of each land portion is outside the tire radial direction with respect to the reference profile. It is formed so as to protrude from the tire.

Further, in the pneumatic tire according to one aspect of the present invention, each of the land portions has protrusions Ha and Hb of 0.2 mm ≦ Ha ≦ 0.4 mm and 0.2 mm ≦ Hb ≦ 0.4 mm. It is preferably in the range.

Further, in the pneumatic tire according to one aspect of the present invention, it is preferable that the protrusion amounts Ha and Hb of the land portion satisfy the relationship of 0.9 ≦ Ha / Hb ≦ 1.1.

Further, in the pneumatic tire according to one aspect of the present invention, the shoulder land portion formed as the outermost section in the tire width direction on the ground contact surface of the tread portion intersects the ground contact surface of the shoulder land portion in the tire circumferential direction. It has a plurality of lug grooves extending in parallel in the tire circumferential direction and dividing the shoulder land portion into a plurality of tire circumferential directions, and the circumferential main groove is a zigzag-shaped number of bends in the tire circumferential direction. However, it is preferable to satisfy the relationship of n or n / 2 with respect to the number of sections n in the tire circumferential direction of the shoulder land portion by the lug groove.

Further, in the pneumatic tire according to one aspect of the present invention, it is preferable that the circumferential main groove is arranged within a range of 30% of the ground contact width centered on the equator surface of the tire.

Further, in the pneumatic tire according to one aspect of the present invention, the circumferential main groove is formed by arranging a plurality of triangular chamfered portions having a zigzag shape that opens to the ground plane at the groove opening end in the tire circumferential direction. It is preferable to have.

Further, in the pneumatic tire according to one aspect of the present invention, the circumferential main groove has the tire width direction dimension Wg of the chamfered portion in the range of 1.0 mm ≦ Wg ≦ 3.5 mm, and the tire radial direction dimension. It is preferable that Lg is in the range of 1.0 mm ≦ Lg ≦ 3.0 mm.

Further, in the pneumatic tire according to one aspect of the present invention, each of the land portions on both sides in the tire width direction with the circumferential main groove as a boundary has land portion widths Wa and Wb of 0.8 ≦ Wa /. It is preferable to satisfy the relationship of Wb ≦ 1.5.

According to the present invention, since the ground contact surfaces of the respective land portions on both sides in the tire width direction with the zigzag-shaped circumferential main groove as a boundary are formed so as to project outward in the tire radial direction with respect to the reference profile, each land is formed. It is possible to secure the ground contact length of the central portion in the tire width direction of the portion, thereby ensuring the ground contact pressure of each land portion. As a result, non-uniformity of the ground contact pressure in the vicinity of the groove edge of the zigzag-shaped circumferential main groove is suppressed, so that the ground contact action is improved and the steering stability performance on a dry road surface can be improved. In addition, since the non-uniformity of the ground pressure near the groove edge of the zigzag-shaped circumferential main groove is suppressed, the water removal action on the circumferential main groove is improved, and the steering stability performance on a wet road surface is improved. be able to. As a result, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view of a tread portion of a pneumatic tire according to an embodiment of the present invention. FIG. 3 is a detailed view of the tread portion of FIG. FIG. 4 is a detailed view of the tread portion of FIG. FIG. 5 is a detailed perspective view of the tread portion. FIG. 6 is a plan view of the tread portion of the pneumatic tire of another example according to the embodiment of the present invention. FIG. 7 is a chart showing the results of a performance evaluation test of a pneumatic tire according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within a range self-evident by those skilled in the art.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to the present embodiment. FIG. 2 is a plan view of the tread portion of the pneumatic tire according to the present embodiment. FIG. 3 is a detailed view of the tread portion of FIG. FIG. 4 is a detailed view of the tread portion of FIG. FIG. 5 is a detailed perspective view of the tread portion. FIG. 6 is a plan view of the tread portion of the pneumatic tire of another example according to the present embodiment.

In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial inside means the side toward the rotation axis in the tire radial direction and the tire radial outside. Refers to the side away from the rotation axis in the tire radial direction. The tire circumferential direction refers to a circumferential direction centered on a rotation axis. The tire width direction means a direction parallel to the rotation axis, the inside in the tire width direction is the side toward the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the outside in the tire width direction is in the tire width direction. The side away from the tire equatorial surface CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL is the center of the pneumatic tire 1 in the tire width direction. The position in the tire width direction coincides with the position in the tire width direction. The tire equatorial line refers to a line on the tire equatorial plane CL and along the tire circumferential direction of the pneumatic tire 1, and in the present embodiment, the same code "CL" as the tire equatorial plane is attached.

As shown in FIG. 1, the pneumatic tire 1 of the present embodiment has a tread portion 2, shoulder portions 3 on both sides thereof, a sidewall portion 4 and a bead portion 5 sequentially continuous from each shoulder portion 3. ing. Further, the pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

The tread portion 2 is made of a rubber material (tread rubber) and is exposed on the outermost side of the pneumatic tire 1 in the tire radial direction, and the outer peripheral surface thereof serves as the contour of the pneumatic tire 1. The outer peripheral surface of the tread portion 2 is a surface that can come into contact with the road surface mainly during traveling, and is configured as a ground contact surface 10.

The shoulder portion 3 is a portion on both outer sides of the tread portion 2 in the tire width direction. Further, the sidewall portion 4 is exposed to the outermost side in the tire width direction of the pneumatic tire 1. Further, the bead portion 5 has a bead core 15 and a bead filler 16. The bead core 15 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 16 is a rubber material arranged in a space formed by folding back the end portion of the carcass layer 6 in the tire width direction at the position of the bead core 15.

In the carcass layer 6, each end in the tire width direction is folded back from the inside in the tire width direction to the outside in the tire width direction by a pair of bead cores 15 and is hung in a toroid shape in the tire circumferential direction to form a tire frame. It is a thing. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged side by side with an angle in the tire circumferential direction while having an angle with respect to the tire circumferential direction along the tire meridian direction with a coated rubber. The carcass cord is made of, for example, organic fibers such as polyester, rayon and nylon. The carcass layer 6 is provided with at least one layer.

The belt layer 7 has a multi-layer structure in which at least two layers of belts 7a and 7b are laminated, is arranged on the outer periphery of the carcass layer 6 in the tire radial direction in the tread portion 2, and covers the carcass layer 6 in the tire circumferential direction. Is. The belts 7a and 7b are formed by coating a plurality of cords (not shown) arranged side by side at a predetermined angle (for example, 20 ° to 30 °) with respect to the tire circumferential direction with a coated rubber. The cord consists of, for example, steel or organic fibers such as polyester, rayon and nylon. Further, the overlapping belts 7a and 7b are arranged so that their cords intersect with each other.

The belt reinforcing layer 8 is arranged outside the outer circumference of the belt layer 7 in the tire radial direction and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by coating a plurality of cords (not shown) arranged side by side in the tire width direction substantially parallel to the tire circumferential direction with coated rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon or nylon, and the angle of the cord is within ± 5 ° with respect to the tire circumferential direction. The belt reinforcing layer 8 shown in FIG. 1 is arranged so as to cover the entire belt layer 7. The configuration of the belt reinforcing layer 8 is not limited to the above, and is not specified in the drawing, but has a configuration arranged so as to cover only the end portion of the belt layer 7 in the tire width direction, or has, for example, two reinforcing layers. , The reinforcing layer on the inner side in the tire radial direction is formed larger in the tire width direction than the belt layer 7 and is arranged so as to cover the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction is the end portion in the tire width direction of the belt layer 7. Even if it is arranged so as to cover only the tires, or for example, it has two reinforcing layers and each reinforcing layer is arranged so as to cover only the end portion of the belt layer 7 in the tire width direction. Good. That is, the belt reinforcing layer 8 overlaps at least the end portion of the belt layer 7 in the tire width direction. Further, the belt reinforcing layer 8 is provided by winding, for example, a strip material having a width of about 10 mm in the tire circumferential direction.

The internal structure of the pneumatic tire 1 described above shows a typical example of the pneumatic tire 1, but the internal structure is not limited to this.

The pneumatic tire 1 of the present embodiment has a designated mounting direction with respect to the vehicle. That is, when the pneumatic tire 1 of the present embodiment is mounted on a vehicle, the orientation with respect to the outside and the inside of the vehicle is specified in the tire width direction. The designation of the orientation is not specified in the figure, but is indicated by, for example, an index provided in the sidewall portion 4. Therefore, when mounted on a vehicle, the side facing the outside of the vehicle is the outside of the vehicle, and the side facing the inside of the vehicle is the inside of the vehicle. The designation of the outside of the vehicle and the inside of the vehicle is not limited to the case where the vehicle is mounted on the vehicle. For example, when the rim is assembled, the orientation of the rim with respect to the outside and the inside of the vehicle is determined in the tire width direction. Therefore, when the pneumatic tire 1 is rim-assembled, the orientation with respect to the outside of the vehicle and the inside of the vehicle is specified in the tire width direction.

The ground contact surface 10 of the tread portion 2 is formed with four circumferential main grooves 20 extending in the tire circumferential direction and continuous over the entire circumference of the tire in the tire width direction.

The circumferential main groove 20 is a groove that is obliged to display a wear indicator specified in JATTA, and has a groove width of 3.0 mm or more and a groove depth of 6.0 mm or more.

The groove width, sipe width, and land width described below are opened in the ground contact surface 10 in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and the specified internal pressure is filled. It is measured as the maximum value of the dimensions of the open ends of both grooves in the tire width direction. In a configuration in which a notch or chamfer 25 is formed on the groove opening edge, the groove width is measured including the notch or chamfer 25 with the groove opening end as the outer edge of the notch or chamfer 25. The groove depth and sipe depth are measured as the maximum values of the dimensions from the ground contact surface 10 to the groove bottom in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. Will be done.

The specified rim is a "standard rim" specified by JATTA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The specified internal pressure is the "maximum air pressure" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. The specified load is the "maximum load capacity" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

Two main grooves 20 in the circumferential direction are arranged on the outer side in the tire width direction with the tire equatorial plane CL as a boundary. On the outside of the vehicle, the circumferential main groove 20 near the tire equatorial plane CL is called the outer center main groove (which can also be called the center main groove) 21, and the outer center main groove 21 is the outer circumferential main groove in the tire width direction. The groove 20 is called an outer shoulder main groove (also called a shoulder main groove) 23. Inside the vehicle, the circumferential main groove 20 near the tire equatorial surface CL is called the inner center main groove (also called the center main groove) 22, and the inner center main groove 22 is called the outer circumferential main groove 20 in the tire width direction. Is called an inner shoulder main groove (also called a shoulder main groove) 24.

In the present embodiment, the circumferential main groove 20 is formed in a zigzag shape in which the outer center main groove 21 is bent along the tire circumferential direction at regular intervals on both sides in the tire width direction. The other inner center main groove 22, the outer shoulder main groove 23, and the inner shoulder main groove 24 are formed linearly in the tire circumferential direction. As shown in FIGS. 4 and 5, the outer center main groove 21 has a triangular chamfered portion 25 having a long portion 25a and a short portion 25b arranged on the ground contact surface 10 at the groove opening end in the tire circumferential direction. The long portion 25a and the short portion 25b of the chamfered portion 25 are arranged point-symmetrically at the open ends of both grooves, so that the chamfered portion 25 is formed in a zigzag shape. Although not clearly shown in the drawing, the outer center main groove 21 has a triangular recess having a long portion 25a and a short portion 25b in a plan view communicating with the ground contact surface 10 and the groove bottom in the groove wall. The grooves themselves may be formed in a zigzag shape by being formed side by side in the tire circumferential direction and having the elongated portions 25a and the short portions 25b of the recesses arranged point-symmetrically on both groove walls.

Further, on the ground contact surface 10 of the tread portion 2, five land portions 30 arranged in the tire width direction are formed by four circumferential main grooves 20 (21, 22, 23, 24). The land portion 30 on the tire equatorial plane CL formed between the outer center main groove 21 and the inner center main groove 22 is referred to as a center land portion 31. On the outside of the vehicle, the land portion 30 formed between the outer center main groove 21 and the outer shoulder main groove 23 is called the outer middle land portion (also called the middle land portion) 32, and the outer shoulder main groove 23 The land portion 30 formed on the outer side in the tire width direction is referred to as an outer shoulder land portion (also referred to as a shoulder land portion) 34. On the inside of the vehicle, the land portion 30 formed between the inner center main groove 22 and the inner shoulder main groove 24 is called the inner middle land portion (also called the middle land portion) 33, and the inner shoulder main groove 24 The land portion 30 formed on the outer side in the tire width direction is referred to as an inner shoulder land portion (also referred to as a shoulder land portion) 35. The outer shoulder main groove 23 and the inner shoulder main groove 24 are respectively located on the ground contact end T.

The ground contact end T is both outermost ends in the tire width direction of the ground contact region, and in FIG. 2, the ground contact end T is continuously shown in the tire circumferential direction. In the ground contact area, when the pneumatic tire 1 was rim-assembled on the specified rim, the specified internal pressure was applied, and 70% of the specified load was applied, the ground contact surface 10 of the tread portion 2 of the pneumatic tire 1 dried. This is the area that touches the flat road surface.

Only the sipe 41 is formed on the ground plane 10 of the center land portion 31. One end of the sipe 41 communicates with the inner center main groove 22 and extends to the CL side of the tire equatorial plane (inside in the tire width direction), and the other end is terminated in the ground contact surface 10 of the center land portion 31. There is. A plurality of sipes 41 are arranged at intervals in the tire circumferential direction. The sipe 41 has a sipe width in the range of 0.6 mm or more and 1.8 mm or less, and a sipe depth in the range of 3.0 mm or more and 7.0 mm or less. The sipe 41 is closed when the ground contact surface 10 touches the ground. The sipe 41 secures tread rigidity and contributes to improvement of steering stability performance on a dry road surface, as compared with a configuration in which a plurality of lug grooves are arranged in the tire circumferential direction in the center land portion 31. Further, the sipe 41 has an inclination angle with respect to the tire circumferential direction within a range of 45 deg or more and 80 deg or less. By ensuring an inclination angle of 45 deg or more, the sipe 41 contributes to suppressing the occurrence of chipping wear, and by ensuring 80 deg or less, the sipe 41 contributes to the improvement of steering stability performance on a wet road surface due to the edge effect.

The sipe 41 preferably has a relationship of 0.30 ≦ L1 / Wcc ≦ 0.60 between the dimension L1 in the tire width direction and the land width Wcc of the center land portion 31. The land width Wcc of the center land portion 31 is a dimension in the tire width direction of the ground contact surface 10 excluding the chamfered portion 25 in the circumferential main groove 20, and is also referred to as a ground contact width that can actually touch the road surface. Hereinafter, the definition of the land width of other land areas is the same. The sipe 41 secures the water removal action by 0.30 ≦ L1 / Wcc and contributes to the improvement of the steering stability performance on the wet road surface, and the rigidity of the center land portion 31 is increased by L1 / Wcc ≦ 0.60. It secures and contributes to steering stability performance on dry road surfaces.

The outer middle land portion 32 is formed with only the lug groove 51 and the sipe 42 on the ground contact surface 10.

One end of the lug groove 51 communicates with the outer shoulder main groove 23 and extends inward in the tire width direction, and the other end is terminated in the ground contact surface 10 of the outer middle land portion 32. The lug groove 51 is formed so as to extend mainly in the tire width direction in a long shape, and a bent portion is provided at the other end so as to extend mainly in the tire circumferential direction in a short shape. A plurality of lug grooves 51 are arranged at intervals in the tire circumferential direction. The lug groove 51 has a sipe (not shown) formed at the bottom of the groove along a long direction, and a chamfer is formed on the ground contact surface 10 side of the sipe, thereby forming the lug groove 51 in the above configuration. .. The chamfers may be on either side of the sipe width or on only one side of the sipe width. The lug groove 51 has a sipe width of 0.3 mm or more and 1.5 mm or less, and a sipe depth from the contact patch 10 of the sipe within a range of 3.3 mm or more and 4.5 mm or less. In the lug groove 51, the chamfer depth of the sipe depth is within the range of 1.0 mm or more and 3.0 mm or less, and the chamfer width is within the range of 1.5 mm or more and 4.5 mm or less. is there. The lug groove 51 closes only the sipes when the ground contact surface 10 touches the ground.

The lug groove 51 preferably has a relationship of 0.65 ≦ L2 / Wco ≦ 0.85 between the dimension L2 in the tire width direction and the land width Wco of the outer middle land portion 32. The lug groove 51 secures a water removing action by 0.65 ≦ L2 / Wco and contributes to the improvement of steering stability performance on a wet road surface, and by L2 / Wco ≦ 0.85, the outer middle land portion 32 It secures rigidity and contributes to steering stability performance on dry road surfaces. In particular, since the lug groove 51 is arranged at the outer edge portion in the tire width direction (ground contact end T side) where the contribution of water removal action is high in the outer middle land portion 32, the steering stability performance on a wet road surface is improved. Contribution is high.

The sipe 42 is singly arranged between the end portions of the lug grooves 51 adjacent to each other in the tire circumferential direction, and extends mainly in the tire circumferential direction. The sipe 42 does not communicate with the lug groove 51 and the circumferential main groove 20, and both ends thereof are terminated within the ground contact surface 10 of the outer middle land portion 32. The sipe 42 extends parallel to the long portion 25a of the chamfered portion 25 of the outer center main groove 21. The sipe 42 has a sipe width in the range of 0.6 mm or more and 1.8 mm or less, and a sipe depth in the range of 3.0 mm or more and 7.0 mm or less. The sipe 42 is closed when the ground contact surface 10 touches the ground. As described above, the sipe 42 is arranged between the lug groove 51 having the dimension L2 in the tire width direction and the end portion of the lug groove 51, so that the arrangement relationship between the lug groove 51 and the circumferential main groove 20 is optimized. Therefore, the rigidity of the outer middle land portion 32 is made uniform, which contributes to steering stability performance on a dry road surface.

The inner middle land portion 33 is formed with only the lug groove 52 and the sipe 43 on the ground contact surface 10.

One end of the lug groove 52 communicates with the inner shoulder main groove 24 and extends inward in the tire width direction, and the other end is terminated in the ground contact surface 10 of the inner middle land portion 33. The lug groove 52 is formed so as to extend in a long shape mainly in the tire width direction. A plurality of lug grooves 52 are arranged at intervals in the tire circumferential direction. The lug groove 52 is formed in the above configuration by forming a sipe (not shown) along the elongated direction at the bottom of the groove and forming a chamfer on the ground contact surface 10 side of the sipe. .. The chamfers may be on either side of the sipe width or on only one side of the sipe width. The lug groove 52 has a sipe width of 0.3 mm or more and 1.5 mm or less, and a sipe depth from the contact patch 10 of the sipe within a range of 3.3 mm or more and 4.5 mm or less. In the lug groove 51, the chamfer depth of the sipe depth is within the range of 1.0 mm or more and 3.0 mm or less, and the chamfer width is within the range of 1.5 mm or more and 4.5 mm or less. is there. The lug groove 51 closes only the sipes when the ground contact surface 10 touches the ground.

The lug groove 52 preferably has a relationship of 0.60 ≦ L3 / Wci ≦ 0.70 between the dimension L3 in the tire width direction and the land width Wci of the inner middle land portion 33. The lug groove 52 secures the water removing action by 0.60 ≦ L3 / Wci and contributes to the improvement of the steering stability performance on the wet road surface, and the inner middle land portion 33 by L3 / Wci ≦ 0.70. It secures rigidity and contributes to steering stability performance on dry road surfaces.

One end of the sipe 43 communicates with the inner center main groove 22 and extends outward in the tire width direction, and the other end is terminated in the ground contact surface 10 of the inner middle land portion 33. A plurality of sipes 43 are arranged at intervals in the tire circumferential direction. The sipe 43 has a sipe width in the range of 0.6 mm or more and 1.8 mm or less, and a sipe depth in the range of 3.0 mm or more and 7.0 mm or less. The sipe 43 is closed when the ground contact surface 10 touches the ground. The sipes 43 are alternately arranged with respect to the lug grooves 52 in the tire circumferential direction. As a result, as compared with the configuration in which only the lug groove or only the sipe is arranged in the tire circumferential direction, the water removal action is ensured, which contributes to the improvement of the steering stability performance on a wet road surface, and the inner middle land portion 33. It contributes to the improvement of steering stability performance on dry road surface by ensuring the rigidity balance of. In particular, the lug groove 52 is arranged at the outer edge portion in the tire width direction (ground contact end T side) where the contribution of water removal action is high in the inner middle land portion 33, and the sipe 43 contributes to the improvement of rigidity in the inner middle land portion 33. By arranging the tire on the inner edge in the high tire width direction (CL side of the tire equatorial plane), it is possible to effectively enhance the mutual balance between the steering stability performance on a wet road surface and the steering stability performance on a dry road surface.

The sipe 43 preferably has a relationship of 0.20 ≦ L4 / Wci ≦ 0.25 between the dimension L4 in the tire width direction and the land width Wci of the inner middle land portion 33. The sipe 43 secures the water removal action by 0.20 ≦ L4 / Wci and contributes to the improvement of steering stability performance on a wet road surface, and the rigidity of the inner middle land portion 33 by L4 / Wci ≦ 0.25. Contributes to steering stability performance on dry roads.

The sipe 43 and the lug groove 52 are arranged so as not to overlap each other when viewed in the tire circumferential direction. Specifically, the dimension D2 in the tire width direction between the end of the sipe 43 and the end of the lug groove 52 is 0.05 ≦ D2 / Wci ≦ 0.20 with respect to the land width Wci of the inner middle land 33. It is preferably in the range. As a result, the rigidity of the inner middle land portion 33 is ensured as compared with the configuration in which the two overlap each other when viewed in the tire circumferential direction, which contributes to the improvement of steering stability performance on a dry road surface.

Further, the sipe 43 of the inner middle land portion 33 and the sipe 41 of the center land portion 31 are inclined in the same direction with respect to the tire circumferential direction. Further, the sipe 43 and the sipe 41 extend along a mutual extension line, and one ends communicating with the inner center main groove 22 are provided so as to face each other with the inner center main groove 22 in between. As a result, the sipe 43 and the sipe 41 secure the water removing action and contribute to the improvement of the steering stability performance on the wet road surface.

The outer shoulder land portion 34 is formed with only the lug groove 53 and the sipe 44 on the ground contact surface 10.

The lug groove 53 intersects the ground contact end T from the outside in the tire width direction and extends inward in the tire width direction, and the extending end does not communicate with the outer shoulder main groove 23 and is inside the contact patch 10 of the outer shoulder land portion 34. It is provided by terminating with. A plurality of lug grooves 53 are arranged at intervals in the tire circumferential direction. The lug groove 53 has a groove width in the range of 1.5 mm or more and 4.5 mm or less, and a groove depth in the range of 55% or more and 80% or less of the groove depth of the outer shoulder main groove 23.

The lug groove 53 preferably has a relationship of 0.50 ≦ L5 / Wso ≦ 0.85 between the dimension L5 inside in the tire width direction from the ground contact end T and the land width Wso of the outer shoulder land portion 34. The lug groove 53 secures a water removing action by 0.50 ≦ L5 / Wso and contributes to the improvement of steering stability performance on a wet road surface, and by L5 / Wso ≦ 0.85, the outer shoulder land portion 34 It secures rigidity and contributes to steering stability performance on dry road surfaces. The land width Wso of the outer shoulder land portion 34 is a dimension in the tire width direction between the outer edge portion of the outer shoulder main groove 23 in the tire width direction and the ground contact end T on the outer side of the vehicle.

The sipe 44 is provided so that one end communicates with the outer shoulder main groove 23 and extends outward in the tire width direction, and the other end is terminated in the ground contact surface 10 of the outer shoulder land portion 34 without intersecting the ground contact end T. Has been done. A plurality of sipes 44 are arranged at intervals in the tire circumferential direction. The sipe 44 has a sipe width in the range of 0.6 mm or more and 1.8 mm or less, and a sipe depth in the range of 3.0 mm or more and 7.0 mm or less. The sipe 44 closes when the ground contact surface 10 touches the ground. The sipes 44 are alternately arranged with respect to the lug grooves 53 in the tire circumferential direction. As a result, as compared with the configuration in which only the lug groove or only the sipe is arranged in the tire circumferential direction, the water removal action is ensured, which contributes to the improvement of the steering stability performance on a wet road surface, and the outer shoulder land portion 34. It contributes to the improvement of steering stability performance on dry road surface by ensuring the rigidity balance of.

The sipe 44 preferably has a relationship of 0.50 ≦ L6 / Wso ≦ 0.85 between the dimension L6 in the tire width direction and the land width Wso of the outer shoulder land portion 34. The sipe 44 secures the water removal action by 0.50 ≦ L6 / Wso and contributes to the improvement of steering stability performance on a wet road surface, and the rigidity of the outer shoulder land portion 34 by L6 / Wso ≦ 0.85. Contributes to steering stability performance on dry roads.

The sipe 44 and the lug groove 53 are arranged so as to overlap each other when viewed in the tire circumferential direction. Specifically, the dimension D3 in the tire width direction between the end of the sipes 44 and the end of the lug groove 53 that overlap each other is 0.50 ≦ D3 / Wso ≦ 0 with respect to the land width Wso of the outer shoulder land portion 34. It is preferably in the range of .70. As a result, the water removing action is ensured as compared with the configuration in which the two do not overlap each other when viewed in the tire circumferential direction, which contributes to the improvement of the steering stability performance on a wet road surface.

The inner shoulder land portion 35 is formed only with a circumferential narrow groove 61, a lug groove 54, and a sipe 45.

The circumferential narrow groove 61 is a narrow groove extending in the circumferential direction of the tire, and is continuous over the entire circumference of the tire. The circumferential fine groove 61 has a groove width in the range of 0.8 mm or more and 3.0 mm or less, and a groove depth in the range of 0.8 mm or more and 3.0 mm or less. The inner land portion 35 is formed into an inner land portion 351 on the inner side in the tire width direction on the inner shoulder main groove 24 side and an outer land portion 352 on the outer side in the tire width direction on the ground contact end T side by the circumferential groove 61. It is divided.

The dimension D4 in the tire width direction from the outer edge portion of the circumferential groove 61 in the tire width direction to the ground contact end T inside the vehicle and the land width Wsi of the inner shoulder land portion 35 are 0.55 ≦ D4 / Wsi. It is preferable to have a relationship of ≦ 0.85. As a result, the circumferential groove 61 sets the position of the circumferential groove 61 in the tire width direction on the inner shoulder land portion 35, optimizes the water removal action, and improves the steering stability performance on a wet road surface. Contribute. Further, the circumferential groove 61 sets the land width of the inner land portion 351 and the outer land portion 352 in the inner shoulder land portion 35, optimizes the rigidity of the inner land portion 351 and the outer land portion 352, and dries. Contributes to the improvement of steering stability performance on the road surface.

The lug groove 54 intersects the ground contact end T from the outside in the tire width direction and extends inward in the tire width direction, and the extending end does not communicate with the inner shoulder main groove 24 and is inside the contact patch 10 of the inner shoulder land portion 35. It is provided by terminating with. The lug groove 54 penetrates the circumferential narrow groove 61, and the end thereof exists in the ground contact surface 10 of the inner land portion 351. A plurality of lug grooves 54 are arranged at intervals in the tire circumferential direction. The lug groove 54 has a groove width in the range of 1.5 mm or more and 4.5 mm or less, and a groove depth in the range of 55% or more and 80% or less of the groove depth of the inner shoulder main groove 24.

The lug groove 54 preferably has a relationship of 0.60 ≦ L7 / Wsi ≦ 0.85 between the dimension L7 inside in the tire width direction from the ground contact end T and the land width Wsi of the inner shoulder land portion 35. The lug groove 54 secures the water removal action by 0.60 ≦ L7 / Wsi and contributes to the improvement of the steering stability performance on a wet road surface, and the inner shoulder land portion 35 by L7 / Wsi ≦ 0.85. It is rigid and particularly secures the rigidity of the inner land portion 351 and contributes to steering stability performance on a dry road surface. The land width Wsi of the inner shoulder land portion 35 is a dimension in the tire width direction between the outer edge portion of the inner shoulder main groove 24 in the tire width direction and the ground contact end T inside the vehicle.

The sipe 45 is provided so that one end communicates with the inner shoulder main groove 24 and extends outward in the tire width direction, and the other end is terminated in the ground contact surface 10 of the inner shoulder land portion 35 without intersecting the ground contact end T. Has been done. The sipe 45 penetrates the circumferential groove 61 and has an end in the ground plane 10 of the outer land portion 352. A plurality of sipes 45 are arranged at intervals in the tire circumferential direction. The sipe 45 has a sipe width in the range of 0.6 mm or more and 1.8 mm or less, and a sipe depth in the range of 3.0 mm or more and 7.0 mm or less. The sipe 45 closes when the ground contact surface 10 touches the ground. The sipes 45 are alternately arranged with respect to the lug grooves 53 in the tire circumferential direction. As a result, as compared with the configuration in which only the lug groove or only the sipe is arranged in the tire circumferential direction, the water removal action is ensured, which contributes to the improvement of the steering stability performance on a wet road surface, and the inner shoulder land portion 35. It contributes to the improvement of steering stability performance on dry road surface by ensuring the rigidity balance of.

The sipe 45 preferably has a relationship of 0.70 ≦ L8 / Wsi ≦ 0.90 between the dimension L8 in the tire width direction and the land width Wsi of the inner shoulder land portion 35. The sipe 45 secures the water removal action by 0.70 ≦ L8 / Wsi and contributes to the improvement of steering stability performance on a wet road surface, and the rigidity of the inner shoulder land portion 35 by L8 / Wsi ≦ 0.90. In particular, the rigidity of the outer land portion 352 is ensured, which contributes to steering stability performance on a dry road surface.

The sipe 45 and the lug groove 54 are arranged so as to overlap each other when viewed in the tire circumferential direction. As a result, the water removing action is ensured as compared with the configuration in which the two do not overlap each other when viewed in the tire circumferential direction, which contributes to the improvement of the steering stability performance on a wet road surface.

In the pneumatic tire 1 of the present embodiment described above, the outer center main groove 21 which is a zigzag-shaped circumferential main groove 20 extending in the tire circumferential direction on the ground contact surface 10 of the tread portion 2 and the outer center main groove 21 are defined as a boundary. The outer center main groove 21 has a center land portion 31 and an outer middle land portion 32, which are the respective land portions 30 formed on both sides in the tire width direction, and has the center land portion 31 and the outer middle land portion 32. Each of the treads 10 is formed so as to project outward in the tire radial direction with respect to the reference profile.

In the present embodiment, the zigzag-shaped circumferential main groove is, but is not limited to, the outer center main groove 21. For example, the zigzag-shaped circumferential main groove 20 may be the inner center main groove 22, and in this case, the inner center main groove 22 is partitioned on both sides in the tire width direction with the inner center main groove 22 as a boundary. The land portion 30 is a center land portion 31 and an inner middle land portion 33. Further, the zigzag-shaped circumferential main groove 20 may be the outer shoulder main groove 23, and in this case, the outer shoulder main groove 23 is defined as a partition on both sides of the outer shoulder main groove 23 in the tire width direction. The land portion 30 is the outer middle land portion 32 and the outer shoulder land portion 34. Further, the zigzag-shaped circumferential main groove 20 may be the inner shoulder main groove 24. In this case, the inner shoulder main groove 24 is defined as a partition on both sides of the inner shoulder main groove 24 in the tire width direction. The land portion 30 is an inner middle land portion 33 and an inner shoulder land portion 35.

Here, as shown in FIG. 3, the reference profile includes each groove opening end in the zigzag-shaped circumferential main groove 20 and each land portion on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 as a boundary. It is an arc that passes through the other three points of the circumferential main groove 20 and the ground contact end T forming 30.

Specifically, when the zigzag-shaped circumferential main groove 20 is the outer center main groove 21, the ground contact surface 10 of the center land portion 31 and the outer middle land portion 32 formed on both sides of the outer center main groove 21 in the tire width direction. Is formed so as to project outward in the radial direction of the tire. In this case, as shown in FIG. 3, the reference profile PRcc of the center land portion 31 is a meridional cross-sectional view in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. , Each groove opening end P1o, P2o in the outer center main groove 21 which is a zigzag-shaped circumferential main groove 20, and the center land portion of the inner center main groove 22 which is another circumferential main groove 20 forming the center land portion 31. It is an arc that passes through three points of the groove opening end P1i on the 31 side. The ground contact surface 10 of the center land portion 31 is the land of the center land portion 31 which is a dimension in the tire width direction between the groove opening end P1o of the outer center main groove 21 and the groove opening end P1i of the inner center main groove 22. In the portion width Wcc, each groove opening ends P1o and P1i project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hcc of the center land portion 31 is the protrusion difference from the reference profile PRcc with respect to the groove opening ends P1o and P1i which are the ends of the land portion width Wcc in the tire width direction. Further, the reference profile PRco of the outer middle land portion 32 is a zigzag shape in the circumferential direction in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. Each groove opening end P1o, P2o in the outer center main groove 21 which is a groove 20, and a groove opening on the outer middle land portion 32 side of the outer shoulder main groove 23 which is another circumferential main groove 20 forming the outer middle land portion 32. It is an arc that passes through the three points of the end P4o. The ground contact surface 10 of the outer middle land portion 32 is the outer middle land portion 32 which is a dimension in the tire width direction between the groove opening end P2o of the outer center main groove 21 and the groove opening end P3o of the outer shoulder main groove 23. In the land width Wco, each groove opening ends P2o and P3o project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hco of the outer middle land portion 32 is the protrusion difference from the reference profile PRco with respect to the groove opening ends P2o and P3o which are the ends of the land portion width Wco in the tire width direction.

Further, when the zigzag-shaped circumferential main groove 20 is the inner center main groove 22, the ground contact surface 10 of the center land portion 31 and the inner middle land portion 33 formed on both sides of the inner center main groove 22 in the tire width direction is the tire. It is formed so as to project outward in the radial direction. In this case, as shown in FIG. 3, the reference profile PRcc of the center land portion 31 is a meridional cross-sectional view in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. , Each groove opening end P1i, P2i in the inner center main groove 22 which is a zigzag-shaped circumferential main groove 20, and the center land portion of the outer center main groove 21 which is another circumferential main groove 20 forming the center land portion 31. It is an arc that passes through three points of the groove opening end P1o on the 31 side. The ground contact surface 10 of the center land portion 31 is the land of the center land portion 31 which is a dimension in the tire width direction between the groove opening end P1o of the outer center main groove 21 and the groove opening end P1i of the inner center main groove 22. In the portion width Wcc, each groove opening ends P1o and P1i project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hcc of the center land portion 31 is the protrusion difference from the reference profile PRcc with respect to the groove opening ends P1o and P1i which are the ends of the land portion width Wcc in the tire width direction. Further, the reference profile PRci of the inner middle land portion 33 is a zigzag shape in the circumferential direction in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. Each groove opening end P1i, P2i in the inner center main groove 22 which is a groove 20, and a groove opening on the inner middle land portion 33 side of the inner shoulder main groove 24 which is another circumferential main groove 20 forming the inner middle land portion 33. It is an arc that passes through the three points of the end P4i. The ground contact surface 10 of the inner middle land portion 33 is the inner middle land portion 33 which is a dimension in the tire width direction between the groove opening end P2i of the inner center main groove 22 and the groove opening end P3i of the inner shoulder main groove 24. In the land width Wci, the groove openings P2i and P3i project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hci of the inner middle land portion 33 is the protrusion difference from the reference profile PRci with respect to the groove opening ends P2i and P3i which are the ends of the land portion width Wci in the tire width direction.

Further, when the zigzag-shaped circumferential main groove 20 is the outer shoulder main groove 23, the contact patch 10 of the outer middle land portion 32 and the outer shoulder land portion 34 formed on both sides of the outer shoulder main groove 23 in the tire width direction is formed. It is formed so as to project outward in the radial direction of the tire. In this case, as shown in FIG. 3, the reference profile PRco of the outer middle land portion 32 is a meridional cross-sectional view in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. The outer side of each groove opening end P3o, P4o in the outer shoulder main groove 23 which is a zigzag-shaped circumferential main groove 20, and the outer center main groove 21 which is another circumferential main groove 20 forming the outer middle land portion 32. It is an arc that passes through three points of the groove opening end P2o on the middle land portion 32 side. The ground contact surface 10 of the outer middle land portion 32 is the outer middle land portion 32 which is a dimension in the tire width direction between the groove opening end P2o of the outer center main groove 21 and the groove opening end P3o of the outer shoulder main groove 23. In the land width Wco, each groove opening ends P2o and P3o project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hco of the outer middle land portion 32 is the protrusion difference from the reference profile PRco with respect to the groove opening ends P2o and P3o which are the ends of the land portion width Wco in the tire width direction. Further, the reference profile PRso of the outer shoulder land portion 34 is a zigzag shape in the circumferential direction in a no-load state (specified load = 0) in which the pneumatic tire 1 is attached to the specified rim and filled with the specified internal pressure. It is an arc that passes through three points of the groove opening ends P3o and P4o and the ground contact end T on the outside of the vehicle in the outer shoulder main groove 23 that is the groove 20. The ground contact surface 10 of the outer shoulder land portion 34 is the land width of the outer shoulder land portion 34, which is a dimension in the tire width direction between the groove opening end P4o of the outer shoulder main groove 23 and the ground contact end T on the outer side of the vehicle. In Wso, the groove opening end P4o and the ground contact end T on the outside of the vehicle project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hso of the outer shoulder land portion 34 is the protrusion difference from the reference profile PRso with respect to the groove opening end P4o which is the end portion of the land portion width Wso in the tire width direction and the ground contact end T on the outside of the vehicle. ..

Further, when the zigzag-shaped circumferential main groove 20 is the inner shoulder main groove 24, the inner middle land portion 33 and the inner shoulder land portion 35, which are partitioned on both sides of the inner shoulder main groove 24 in the tire width direction, have contact patches 10. It is formed so as to project outward in the radial direction of the tire. In this case, as shown in FIG. 3, the reference profile PRci of the inner middle land portion 33 is a meridional cross-sectional view in a no-load state (specified load = 0) in which the pneumatic tire 1 is mounted on the specified rim and filled with the specified internal pressure. The inside of each groove opening end P3i, P4i in the inner shoulder main groove 24 which is a zigzag-shaped circumferential main groove 20, and the inner center main groove 22 which is another circumferential main groove 20 forming the inner middle land portion 33. It is an arc that passes through three points of the groove opening end P2i on the middle land portion 33 side. The ground contact surface 10 of the inner middle land portion 33 is a dimension in the tire width direction between the outer groove opening end P2i of the inner center main groove 22 in the tire width direction and the groove opening end P3i of the inner shoulder main groove 24. In the land width Wci of the inner middle land portion 33, the groove opening ends P2i and P3i project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hci of the inner middle land portion 33 is the protrusion difference from the reference profile PRci with respect to the groove opening ends P2i and P3i which are the ends of the land portion width Wci in the tire width direction. Further, the reference profile PRsi of the inner shoulder land portion 35 is a zigzag shape in the circumferential direction in a no-load state (specified load = 0) in which the pneumatic tire 1 is attached to the specified rim and filled with the specified internal pressure. It is an arc that passes through three points of the groove opening ends P3i and P4i in the inner shoulder main groove 24 that is the groove 20 and the ground contact end T inside the vehicle. The ground contact surface 10 of the inner shoulder land portion 35 has a dimension in the tire width direction between the outer groove opening end P4i of the inner shoulder main groove 24 in the tire width direction and the ground contact end T inside the vehicle. In the land width Wsi, the groove opening end P4i and the ground contact end T inside the vehicle project outward in the tire radial direction in a gradual curve (or arc) toward the central portion in the tire width direction. That is, in other words, the protrusion amount Hsi of the inner shoulder land portion 35 is the protrusion difference from the reference profile PRsi with respect to the groove opening end P4i which is the end portion of the land portion width Wsi in the tire width direction and the ground contact end T inside the vehicle. ..

Therefore, the pneumatic tire 1 of the present embodiment has a zigzag-shaped circumferential main groove 20 extending in the tire circumferential direction on the ground contact surface 10 of the tread portion 2, and the circumferential main groove 20 with the circumferential main groove 20 as a boundary. Each land portion 30 is formed as a section on both sides in the tire width direction, and each contact patch 10 of each land portion 30 is formed so as to project outward in the tire radial direction with respect to the reference profile.

According to the pneumatic tire 1, the contact patch 10 of each land portion 30 on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 as a boundary is formed so as to project outward in the tire radial direction with respect to the reference profile. Therefore, it is possible to secure the contact patch length of each land portion 30 at the center in the tire width direction, thereby ensuring the contact pressure of each land portion 30. As a result, the non-uniformity of the ground contact pressure near the groove edge of the zigzag-shaped circumferential main groove 20 is suppressed, so that the ground contact action is improved and the steering stability performance on a dry road surface can be improved. In addition, since the non-uniformity of the ground pressure near the groove edge of the zigzag-shaped circumferential main groove 20 is suppressed, the water removing action on the circumferential main groove 20 is improved, and the steering stability performance on a wet road surface is improved. Can be improved. As a result, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion amounts Ha and Hb of each of the land portions 30 on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 as a boundary are 0.2 mm ≦ Ha ≦. It is preferably in the range of 0.4 mm and 0.2 mm ≦ Hb ≦ 0.4 mm.

Here, the protrusion amounts Ha and Hb of each land portion 30 are the protrusion amount Hcc of the center land portion 31 described above, the protrusion amount Hco of the outer middle land portion 32, the protrusion amount Hci of the inner middle land portion 33, and the outside. It corresponds to the protruding amount Hso of the shoulder land portion 34 and the protruding amount Hsi of the inner shoulder land portion 35. That is, the protrusion amount Hcc of the center land portion 31 on both sides of the outer center main groove 21 which is the zigzag shape circumferential main groove 20 in the tire width direction and the protrusion amount Hco of the outer middle land portion 32 are 0.2 mm ≦ Hcc ≦ 0. It is preferably in the range of 0.4 mm and 0.2 mm ≦ Hco ≦ 0.4 mm. Further, the protrusion amount Hcc of the center land portion 31 on both sides of the inner center main groove 22 which is the zigzag shape circumferential main groove 20 in the tire width direction and the protrusion amount Hci of the inner middle land portion 33 are 0.2 mm ≦ Hcc ≦ 0. It is preferably in the range of 0.4 mm and 0.2 mm ≦ Hci ≦ 0.4 mm. Further, the protrusion amount Hco of the outer middle land portion 32 and the protrusion amount Hso of the outer shoulder land portion 34 on both sides of the outer shoulder main groove 23 in the tire width direction, which are the zigzag-shaped circumferential main grooves 20, are 0.2 mm ≦ Hco ≦. It is preferably in the range of 0.4 mm and 0.2 mm ≦ Hso ≦ 0.4 mm. Further, the protrusion amount Hci of the inner middle land portion 33 and the protrusion amount Hsi of the inner shoulder land portion 35 on both sides of the inner shoulder main groove 24 which is the zigzag-shaped circumferential main groove 20 in the tire width direction are 0.2 mm ≦ Hci ≦. It is preferably in the range of 0.4 mm and 0.2 mm ≦ Hsi ≦ 0.4 mm.

According to this pneumatic tire 1, the protrusion amounts Ha and Hb of each land portion 30 on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 as a boundary are set to 0.2 mm or more, so that the center in the tire width direction is set. The contact pressure near the position can be made closer to the contact pressure at both outer positions in the tire width direction, and by setting it to 0.4 mm or less, the protrusion amounts Ha and Hb near the center position in the tire width direction are suppressed. , It is possible to suppress an excessive decrease in the contact pressure at both outer positions in the tire width direction. As a result, the grip force with the road surface can be enhanced, and the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the protrusion amounts Ha and Hb of each land portion 30 on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 as a boundary are 0.9 ≦ Ha / Hb ≦ 1. It is preferable to satisfy the relationship of 1.

According to the pneumatic tire 1, it is possible to suppress excessive fluctuations in the ground contact pressure at each land portion 30 on both sides in the tire width direction with the zigzag-shaped peripheral main groove 20 as a boundary, and these ground contact properties can be improved. As good, the clipping force with the road surface can be increased. As a result, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 2, the zigzag-shaped circumferential main groove 20 (in FIG. 2, the outer center main groove 21) has a zigzag-shaped number of bends in the tire circumferential direction. The outer shoulder land portion 34 and the inner shoulder by the lug grooves 53 and 54 of the shoulder land portion (in the present embodiment, the outer shoulder land portion 34 and the inner shoulder land portion 35) which are defined and formed in the outermost section in the tire width direction. It satisfies n relationships with respect to the number of sections n in the tire circumferential direction of the land portion 35. That is, as shown in FIG. 2, in the zigzag-shaped circumferential main groove 20, the number of bends in the zigzag-shaped tire circumferential direction is the tire circumferential direction of the outer shoulder land portion 34 and the inner shoulder land portion 35 due to the lug grooves 53 and 54. It is the same as the number of sections n of.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 6, the zigzag-shaped circumferential main groove 20 (in FIG. 6, the outer center main groove 21) has a zigzag-shaped number of bends in the tire circumferential direction. The outer shoulders are defined by the lug grooves 53, 55 and the lug grooves 54, 56 of the shoulder land portion (in the present embodiment, the outer shoulder land portion 34 and the inner shoulder land portion 35) formed in the outermost section in the tire width direction. The relationship of n / 2 is satisfied with respect to the number of sections n in the tire circumferential direction of the land portion 34 and the inner shoulder land portion 35. That is, as shown in FIG. 6, in the zigzag-shaped circumferential main groove 20, the number of bends in the zigzag-shaped tire circumferential direction is the tire circumferential direction of the outer shoulder land portion 34 and the inner shoulder land portion 35 due to the lug grooves 53 and 54. It is half of the number of sections n of.

Here, as shown in FIG. 6, the lug groove 55 of the outer shoulder land portion 34 is arranged between the lug grooves 53 and is provided so as to extend beyond the ground contact end T and communicate with the sipe 44. The lug groove 55 has a groove width in the range of 1.5 mm or more and 4.5 mm or less, and a groove depth in the range of 55% or more and 80% or less of the groove depth of the outer shoulder main groove 23. Further, the lug groove 56 of the inner shoulder land portion 35 is arranged between the lug grooves 54, and is provided so as to extend beyond the ground contact end T and communicate with the sipe 45. The lug groove 56 has a groove width in the range of 1.5 mm or more and 4.5 mm or less, and a groove depth in the range of 55% or more and 80% or less of the groove depth of the inner shoulder main groove 24.

According to the pneumatic tire 1, in order to improve the steering stability performance on a wet road surface, and to enhance the water removing action of the outer shoulder land portion 34 and the inner shoulder land portion 35, particularly when turning, it is shown in FIG. As described above, it is preferable that the outer shoulder land portion 34 is provided with the lug grooves 53 and 55, and the inner shoulder land portion 35 is provided with the lug grooves 54 and 56. In this case, since there is a concern that the rigidity of the outer shoulder land portion 34 and the inner shoulder land portion 35 may decrease due to the provision of the lug grooves 53, 55 and the lug grooves 54, 56, the zigzag-shaped circumferential main groove 20 (in FIG. 6). , The number of zigzag-shaped flexes in the tire circumferential direction in the outer center main groove 21) is set to n / 2 with respect to the number of compartments n in the tire circumferential direction of the outer shoulder land portion 34 and the inner shoulder land portion 35. Rigidity near the groove edge of the circumferential main groove 20 of the shape is ensured, and deterioration of steering stability performance on a dry road surface is suppressed. On the other hand, in order to improve the steering stability performance on a dry road surface and to increase the rigidity of the outer shoulder land portion 34 and the inner shoulder land portion 35, as shown in FIG. 2, only the lug groove 53 is provided in the outer shoulder land portion 34. It is preferable to provide only the lug groove 54 on the inner shoulder land portion 35. In this case, since there is a concern that the water removing action of the outer shoulder land portion 34 and the inner shoulder land portion 35 may be reduced because only the lug groove 53 or the lug groove 54 is present, the zigzag-shaped circumferential main groove 20 (in FIG. 6). The number of bends in the zigzag shape tire circumferential direction in the outer center main groove 21) is n with respect to the number of compartments n in the tire circumferential direction of the outer shoulder land portion 34 and the inner shoulder land portion 35, thereby forming the zigzag shape circumference. The water removal action near the groove edge of the directional main groove 20 is ensured, and deterioration of steering stability performance on a wet road surface is suppressed. As a result, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 2, 3 and 6, the zigzag-shaped circumferential main groove 20 (in the present embodiment, the outer center main groove 21) is the tire equatorial plane. It is preferably arranged within the WTC within a range of 30% of the ground contact width centered on CL.

According to the pneumatic tire 1, the area within the WTC within the range of 30% of the contact width centered on the tire equatorial plane CL is the portion where the contact length is the longest, and this portion has a zigzag-shaped circumference having a high water removal effect. By arranging the directional main groove 20, the drainage performance is improved. As a result, the steering stability performance on a wet road surface can be improved.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 4 and 5, the zigzag-shaped circumferential main groove 20 (in the present embodiment, the outer center main groove 21) has a zigzag-shaped groove opening end. It is preferable that a plurality of triangular chamfered portions 25 that open to the ground contact surface 10 are arranged side by side in the tire circumferential direction.

According to the pneumatic tire 1, the rigidity of the groove bottom side of the main groove 20 in the circumferential direction can be ensured by forming the zigzag shape by the chamfered portion 25 at the groove opening end. As a result, it is possible to improve the steering stability performance on a dry road surface while improving the steering stability performance on a wet road surface due to the zigzag shape.

Further, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 4 and 5, the zigzag-shaped circumferential main groove 20 (in the present embodiment, the outer center main groove 21) is the length of the chamfer 25. The tire width direction dimension Wg in the vertical direction is in the range of 1.0 mm ≦ Wg ≦ 3.5 mm, and the tire radial dimension Lg in the depth direction is in the range of 1.0 mm ≦ Lg ≦ 3.0 mm. preferable.

According to the pneumatic tire 1, it is possible to secure the rigidity of the groove bottom side of the circumferential main groove 20 while obtaining the water removing action by the chamfered portion 25. As a result, it is possible to improve the steering stability performance on a dry road surface while improving the steering stability performance on a wet road surface due to the zigzag shape.

Further, in the pneumatic tire 1 of the present embodiment, each land portion 30 on both sides in the tire width direction with the zigzag-shaped circumferential main groove 20 (in the present embodiment, the outer center main groove 21) as a boundary is a land. The portion widths Wa and Wb satisfy the relationship of 0.8 ≦ Wa / Wb ≦ 1.5.

Here, the land widths Wa and Wb of each land portion 30 are the land width Wcc of the center land portion 31, the land width Wco of the outer middle land portion 32, and the land portion width of the inner middle land portion 33. It corresponds to Wci, the land width Wso of the outer shoulder land 34, and the land width Wsi of the inner shoulder 35. That is, the land width Wcc of the center land portion 31 on both sides of the outer center main groove 21 which is the zigzag-shaped circumferential main groove 20 in the tire width direction and the land width Wco of the outer middle land portion 32 are 0.8 ≦ Wcc. It is preferable to satisfy the relationship of / Wco ≦ 1.5. Further, the land width Wcc of the center land portion 31 on both sides of the inner center main groove 22 which is the zigzag-shaped circumferential main groove 20 in the tire width direction and the land width Wci of the inner middle land portion 33 are 0.8 ≦ Wcc. It is preferable to satisfy the relationship of / Wci ≦ 1.5. Further, the land width Wco of the outer middle land portion 32 and the land width Wso of the outer shoulder land portion 34 on both sides of the outer shoulder main groove 23 which is the zigzag-shaped circumferential main groove 20 in the tire width direction are 0.8 ≦ It is preferable to satisfy the relationship of Wco / Wso ≦ 1.5. Further, the land width Wci of the inner middle land portion 33 and the land portion width Wsi of the inner shoulder land portion 35 on both sides of the inner shoulder main groove 24 which is the zigzag-shaped circumferential main groove 20 in the tire width direction are 0.8 ≦ It is preferable to satisfy the relationship of Wci / Wsi ≦ 1.5.

According to the pneumatic tire 1, it is possible to suppress excessive fluctuations in the ground contact pressure at each land portion 30 on both sides in the tire width direction with the zigzag-shaped peripheral main groove 20 as a boundary, and these ground contact properties can be improved. As good, the clipping force with the road surface can be increased. As a result, the steering stability performance on a dry road surface and the steering stability performance on a wet road surface can be improved.

In this embodiment, performance tests on steering stability performance (also referred to as dry performance) on dry road surfaces and steering stability performance (also referred to as wet performance) on wet road surfaces were conducted for a plurality of types of pneumatic tires under different conditions (also referred to as dry performance). (See FIG. 7).

In the performance evaluation test, a pneumatic tire, which is a test tire with a tire designation of 225 / 50R17 98W size specified by JATTA, is assembled to a regular rim with a rim size of 17 x 75J and filled with an internal pressure of 230 kPa to fill a sedan type test vehicle. It was attached to all the rear wheels of.

The method of evaluating the steering stability performance on a dry road surface is to strike a test course on a dry road surface, and a specialized test driver evaluates the feeling of control drive performance, lane change performance, cornering performance, and so on. This evaluation is an index evaluation based on the conventional example (100). This evaluation indicates that the higher the index, the better the steering stability performance on a dry road surface.

The method of evaluating steering stability performance on a wet road surface is to strike a test course on a wet road surface, and a professional test driver evaluates the feeling of control drive performance, lane change performance, cornering performance, and so on. This evaluation is an index evaluation based on the conventional example (100). This evaluation indicates that the higher the index, the better the steering stability performance on a wet road surface.

In FIG. 7, the pneumatic tires of the conventional example and the first to fifteenth embodiments are four circumferential main grooves extending in the tire circumferential direction on the ground contact surface of the tread portion as shown in FIGS. 2 and 6. The outer center main groove, the inner center main groove, the outer shoulder main groove, and the inner shoulder main groove form five land parts in the tire width direction, so that the center land part on the tire equatorial plane is formed. The outer middle land portion on the outside of the vehicle in the center land portion, the outer shoulder land portion on the outer side of the vehicle in the outer middle land portion, the inner middle land portion on the inner side of the vehicle in the center land portion, and the inner middle land portion. It has an inner shoulder tread on the inside of the vehicle. Further, in the pneumatic tires of the conventional example and the first to fifteenth embodiments, the inner center main groove is formed in a zigzag shape.

Then, in the pneumatic tire of the conventional example, the contact patches of the land portions on both sides in the tire width direction with the zigzag-shaped main groove in the circumferential direction as a boundary are on the reference profile. On the other hand, in the pneumatic tires of Examples 1 to 15, the contact patches of the land portions on both sides in the tire width direction with the zigzag-shaped circumferential main groove as a boundary project outward in the tire radial direction with respect to the reference profile. Is formed.

As shown in the test results of FIG. 7, it can be seen that the pneumatic tires of Examples 1 to 15 have improved steering stability performance on a dry road surface and steering stability performance on a wet road surface.

1 Pneumatic tire 2 Tread part 3 Shoulder part 4 Side wall part 5 Bead part 6 Carcus layer 7 Belt layer 7a, 7b Belt 8 Belt reinforcement layer 10 Ground plane 15 Bead core 16 Bead filler 20 Circumferential main groove 21 Outer center main groove 22 Inner center main groove 23 Outer shoulder main groove 24 Inner shoulder main groove 25 Chamfered part 25a Long part 25b Short part 30 Land part 31 Center land part 32 Outer middle land part 33 Inner middle land part 34 Outer shoulder land part 35 Inner shoulder Land 351 Inner land 352 Outer land 41, 42, 43, 44, 45 Sipe 51, 52, 53, 54, 55, 56 Rug groove 61 Circumferential narrow groove CL Tire Equator surface Hcc Center Land protrusion amount Hci Inner middle land area protrusion Hco Outer middle land area protrusion Hsi Inner shoulder land area protrusion Hso Outer shoulder land area protrusion P1o, P2o Outer center main groove groove opening end P1i, P2i Inner center main groove Groove opening end P3o, P4o Outer shoulder main groove groove opening end P3i, P4i Inner shoulder main groove groove opening end PRcc Center land reference profile PRco Outer middle land reference profile PRso Outer shoulder land reference profile PRci Inner Middle land reference profile PRsi Inner shoulder land reference profile T Tread Wcc Center land width Wco Outer middle land land width Wso Outer shoulder land width Wci Inner middle land land Width of the part Wsi Inner shoulder Land width of the land

Claims (9)

A zigzag-shaped main groove extending in the circumferential direction of the tire on the ground contact surface of the tread,
Each land portion formed on both sides in the tire width direction of the circumferential main groove with the circumferential main groove as a boundary, and
Have and
One of the land portions extends in the tire width direction and does not communicate with the circumferential main groove, and an end portion is provided so as to terminate within the ground contact surface of the one land portion so as to provide an interval in the tire circumferential direction. Only sipes that are arranged between a plurality of lug grooves arranged in the tire circumferential direction and the end portions of the lug grooves adjacent to each other in the tire circumferential direction and do not communicate with the lug groove and the circumferential main groove but extend in the tire circumferential direction. Formed,
The other land portion extends in the tire width direction and does not communicate with the circumferential main groove, and an end portion is provided so as to terminate within the ground contact surface of the other land portion so as to provide an interval in the tire circumferential direction. Only multiple sipes are formed in
A pneumatic tire in which the contact patch of each of the land portions projects outward in the tire radial direction with respect to the reference profile. The lug groove provided on one of the land portions has a sipe formed at the bottom of the groove, and a chamfer is formed on the ground contact surface side of the sipe, and the sipe provided on the other land portion has a sipe. The pneumatic tire according to claim 1, wherein the dimension L1 in the tire width direction and the land width Wcc of the other land portion have a relationship of 0.30 ≦ L1 / Wcc ≦ 0.60. The pneumatic tire according to claim 1 or 2 , wherein each of the land portions has protrusions Ha and Hb in the range of 0.2 mm ≦ Ha ≦ 0.4 mm and 0.2 mm ≦ Hb ≦ 0.4 mm. .. The pneumatic tire according to any one of claims 1 to 3, wherein the protrusion amounts Ha and Hb of the land portion satisfy the relationship of 0.9 ≦ Ha / Hb ≦ 1.1. A shoulder land portion formed on the outermost side in the tire width direction on the ground contact surface of the tread portion,
A lug groove that intersects the ground contact surface of the shoulder land portion in the tire circumferential direction and extends in parallel in the tire circumferential direction to divide the shoulder land portion into a plurality of tire peripheral directions.
Have,
Claim that the number of bends in the tire circumferential direction in a zigzag shape satisfies the relationship of n or n / 2 with respect to the number of sections n in the tire circumferential direction of the shoulder land portion by the lug groove. The pneumatic tire according to any one of 1 to 4 . The pneumatic tire according to any one of claims 1 to 5 , wherein the circumferential main groove is arranged within a range of 30% of the ground contact width centered on the equatorial plane of the tire. The circumferential main groove according to any one of claims 1 to 6 , wherein a plurality of triangular chamfered portions having a zigzag shape that opens to a ground contact surface at the groove opening end are formed side by side in the tire circumferential direction. Pneumatic tires. In the circumferential main groove, the tire width direction dimension Wg of the chamfered portion is in the range of 1.0 mm ≦ Wg ≦ 3.5 mm, and the tire radial dimension Lg is in the range of 1.0 mm ≦ Lg ≦ 3.0 mm. The pneumatic tire according to claim 7 . Claims 1 to 8 in which the land portions on both sides in the tire width direction with the circumferential main groove as a boundary satisfy the relationship of 0.8 ≦ Wa / Wb ≦ 1.5 in the respective land widths Wa and Wb. Pneumatic tire according to any one of.

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